Spherical polyhedral strontium titanate single crystal particle as well as preparation method and application thereof
Spherical polyhedral strontium titanate single crystal particles were prepared by hydrothermal method, exposing multiple micro crystal faces, which solved the problem of low photocatalytic efficiency of strontium titanate materials and achieved a highly efficient photocatalytic water splitting hydrogen production effect.
Patent Information
- Application Number
- CN202511738597.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-03-03
AI Technical Summary
Existing strontium titanate materials have low photocatalytic efficiency and limited exposed crystal faces in the field of photocatalytic water splitting for hydrogen production, making it difficult to achieve efficient photocarrier separation.
Spherical polyhedral strontium titanate single crystal particles were prepared by hydrothermal method. Titanium source, strontium source and aluminum source were mixed under alkaline conditions. The formation of surface crystal faces was controlled by morphology modifier, exposing multiple micro crystal faces, especially (100), (110) and (111) crystal faces, with crystal face size less than 10 nm.
It achieves a high rate of hydrogen production from water splitting under sunlight, improves photocarrier separation efficiency, and has crystal planes with no obvious boundaries, approaching the characteristics of infinitely many crystal planes.
Smart Images
Figure CN121591248A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterial preparation technology, and relates to a spherical polyhedral strontium titanate particle, specifically to a spherical polyhedral strontium titanate single crystal particle and its preparation method and application. Background Technology
[0002] Hydrogen, as a green, zero-pollution, and highly efficient energy source, is an ideal new energy choice for the future. After years of development and long-term efforts, extensive research and practice have been conducted in the fields of hydrogen production, storage, transportation, and end-use applications. Photocatalytic water splitting for hydrogen production is an emerging, environmentally friendly, and low-carbon pure green hydrogen production technology. Compared with water electrolysis, it features a simpler process, higher energy conversion rate, and lower cost. Among commonly used photocatalysts for water splitting, titanium dioxide is a key component. The research results on photocatalytic water splitting using TiO2 electrodes in 1972 opened the door to the world of photocatalysis. Since then, researchers in chemistry, physics, materials science, and other fields have conducted extensive research on semiconductor materials and special crystal materials in areas such as solar energy conversion and storage, photochemical synthesis, photocatalytic water splitting for hydrogen production, and photocatalytic degradation. However, titanium dioxide suffers from low photocatalytic efficiency and structural instability.
[0003] Strontium titanate (SrTiO3) is an excellent photocatalytic material with high temperature resistance and high ultraviolet light absorption efficiency. It possesses a suitable band gap and hydrogen evolution and oxygen evolution potentials, with a band gap of 3.2 eV. Therefore, SrTiO3 is an ideal material for photocatalytic water splitting to produce hydrogen. Strontium titanate also has a high refractive index (n=2.409) and strong dispersion (0.190), and is often used as a diamond analog in precision optical devices. Furthermore, it is widely used in the field of high-temperature superconducting substrates due to its high lattice matching.
[0004] Polyhedral SrTiO3, when applied to photocatalysis, can significantly improve the photocatalytic efficiency of the system, especially in the field of photocatalytic water splitting for hydrogen production, where its high catalytic performance has been verified. More crystal facets can induce anisotropic migration of charge carriers, thus improving carrier separation efficiency and enhancing the photocatalytic performance of SrTiO3. Although many polyhedral morphologies have been developed, including hexahedrons, octahedra, and icosahedrons, the icosahedron has the most exposed crystal facets, revealing (100), (110), and (111) facets. However, the variety of exposed crystal facets remains limited, and no SrTiO3 crystal particles with more exposed crystal facets have been prepared or reported to date. Theoretically, the surface of spherical crystal particles consists of countless crystal facets with different orientations, which can greatly improve photocarrier separation efficiency, but this has not yet been reported. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide spherical polyhedral strontium titanate single crystal particles, their preparation method, and applications. The present invention employs a hydrothermal method, utilizing titanium, strontium, and aluminum sources to prepare regular spherical polyhedral strontium titanate single crystal particles, achieving effective exposure of micro-crystal planes such as (100), (110), and (111), with crystal plane sizes less than 10 nm. When applied to photocatalysis, these particles exhibit highly efficient photocatalytic water splitting and hydrogen production rates under sunlight.
[0006] To achieve this objective, the present invention employs the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing spherical polyhedral strontium titanate single crystal particles, the method comprising:
[0008] A mixed solution was obtained by ultrasonic dispersion of a titanium source, a strontium source, a morphology modifier, an aluminum source, and an alkaline solution.
[0009] The mixed solution was subjected to a hydrothermal reaction, followed by washing and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
[0010] This invention employs a hydrothermal method, utilizing titanium, strontium, and aluminum sources, to prepare regular spherical polyhedral strontium titanate single crystal particles under alkaline conditions. This method effectively exposes multiple micro-crystal faces, and the spherical particles have no obvious boundaries, exhibiting characteristics close to an infinite number of crystal faces. Their surfaces can be considered as being composed of countless crystal faces with different orientations. Therefore, the anisotropic migration effects of photocarriers in the spherical polyhedral strontium titanate single crystal particles are more pronounced.
[0011] More specifically, the morphology modifier is used to control the formation of regular crystal planes on the surface of strontium titanate; the aluminum source has the following functions: (1) supplementing lattice defects; (2) inhibiting the formation of large crystal planes on the particle surface and promoting the formation of small crystal planes with a size of less than 10 nm.
[0012] As a preferred embodiment of the present invention, the titanium source includes any one or a combination of at least two of TiO2, TiCl4, or tetrabutyl titanate. Typical but non-limiting combinations include: a combination of TiO2 and TiCl4, a combination of TiO2 and tetrabutyl titanate, a combination of TiCl4 and tetrabutyl titanate, or a combination of TiO2, TiCl4, and tetrabutyl titanate.
[0013] Preferably, the strontium source includes any one or a combination of at least two of Sr(OH)2, SrCl2, or SrCO3. Typical but non-limiting combinations include: a combination of Sr(OH)2 and SrCl2, a combination of Sr(OH)2 and SrCO3, a combination of SrCl2 and SrCO3, or a combination of Sr(OH)2, SrCl2, and SrCO3.
[0014] Preferably, the molar ratio of the titanium source to the strontium source is 1:0.8 to 1.2, for example, it can be 1:0.8, 1:0.85, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0015] Preferably, the morphology modifier comprises any one or a combination of at least two of ethylene glycol, glycerol, 1,2-butanediol, or propylene glycol. Typical but non-limiting combinations include: a combination of ethylene glycol and glycerol, a combination of ethylene glycol, glycerol, and 1,2-butanediol, a combination of glycerol, 1,2-butanediol, and propylene glycol, or a combination of ethylene glycol, glycerol, 1,2-butanediol, and propylene glycol.
[0016] Preferably, the content of the morphology modifier in the mixed solution is 1~3wt%, for example, it can be 1wt%, 1.4wt%, 1.8wt%, 2.2wt%, 2.6wt% or 3wt%, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0017] Preferably, the aluminum source includes Al2O3 and / or Al(OH)3.
[0018] Preferably, the average particle size of the aluminum source is 50~500 nm, for example, it can be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm or 500 nm, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0019] Preferably, the content of aluminum source in the mixed solution is 0.1~0.5wt%, for example, it can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% or 0.5wt%, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0020] In this invention, the aluminum source is one of the important factors affecting the morphology of strontium titanate single crystal particles. If the amount of aluminum source added is too high, it will lead to small protrusions on the surface of strontium titanate; if the amount of aluminum source added is too low, it will lead to small depressions on the surface of strontium titanate and strontium titanate lattice defects.
[0021] Preferably, the concentration of the alkaline solution is 1~2 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, but is not limited to the listed values. Other values not listed within the range are also applicable.
[0022] Preferably, the alkaline solution includes any one of an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, or an aqueous solution of lithium hydroxide.
[0023] Preferably, the pH value of the mixed solution is 9 to 12, for example, it can be 9, 9.5, 10, 10.5, 11, 11.5 or 12, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0024] It is worth noting that the preparation method of the mixed solution of the present invention includes: first mixing a titanium source, a strontium source and an alkaline solution to obtain a first solution; then sequentially adding a morphology modifier and an aluminum source, and ultrasonically dispersing to obtain a mixed solution.
[0025] As a preferred embodiment of the present invention, the temperature of the hydrothermal reaction is 150~200℃, for example, it can be 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0026] Preferably, the heating rate of the hydrothermal reaction is 5~10℃ / min, for example, it can be 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.
[0027] Preferably, the hydrothermal reaction time is 24~48h, for example, it can be 24h, 28h, 32h, 36h, 40h, 44h or 48h, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0028] Preferably, the hydrothermal reaction is accompanied by stirring, and the stirring speed is 100~150 r / min, for example, it can be 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min or 150 r / min, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0029] In this invention, the reaction raw materials (titanium source, strontium source, morphology modifier, and aluminum source) are dissolved in an alkaline solution and crystallized through a hydrothermal reaction to generate strontium titanate particles. During the reaction, the morphology modifier is used to make the particles grow into polyhedral small particles. During the growth process, due to the incorporation of a large number of aluminum atoms into the crystal lattice, the crystal face growth rate of different crystallization directions is consistent, and finally spherical strontium titanate is obtained. If the temperature of the hydrothermal reaction is too high, the crystallization rate will be slow and the morphology will be irregular. If the temperature is too low, the strontium titanate perovskite structure will not be formed.
[0030] As a preferred embodiment of the present invention, the number of washing cycles is 3 to 5 times, for example, 3 times, 4 times or 5 times.
[0031] Preferably, the washing solution used for washing includes water and / or anhydrous ethanol.
[0032] Preferably, the drying temperature is 80~100℃, for example, it can be 80℃, 84℃, 88℃, 92℃, 96℃ or 100℃, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0033] Preferably, the drying time is 5 to 10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0034] In a second aspect, the present invention provides a spherical polyhedral strontium titanate single crystal particle, wherein the spherical polyhedral strontium titanate single crystal particle is obtained by the preparation method provided in the first aspect.
[0035] Preferably, the average particle size of the spherical polyhedral strontium titanate single crystal particles is 200~500nm, for example, it can be 200nm, 250nm, 300nm, 350nm, 400nm, 450nm or 500nm, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0036] Thirdly, the present invention provides a strontium titanate catalyst, the strontium titanate catalyst comprising spherical polyhedral strontium titanate single crystal particles obtained by the preparation method provided in the first aspect, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles;
[0037] The co-catalysts include Rh, Cr, and Co.
[0038] As an effective technical solution of the present invention, the preparation method of the strontium titanate catalyst includes:
[0039] (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate;
[0040] (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst.
[0041] In this invention, solid-state heat treatment is used to promote recrystallization on the surface of strontium titanate particles under high temperature conditions, reducing crystal defects and making the surface structure more regular; then, by depositing Rh, Cr and Co on the surface of the intermediate, the efficiency of photocatalytic decomposition of strontium titanate to produce hydrogen is improved.
[0042] As a preferred technical solution of the present invention, the temperature of the solid phase heat treatment in step (1) is 800~900℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0043] Preferably, the heat treatment time of the solid phase heat treatment in step (1) is 5~10h, for example, it can be 5h, 6h, 7h, 8h, 9h or 10h, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0044] In this invention, if the solid-state heat treatment temperature is too high, it will cause surface defects of the strontium titanate single crystal particles, forming a stepped morphology; if the temperature is too low, surface recrystallization cannot be completed.
[0045] It is worth noting that the solid-phase heat treatment described in this invention also includes sequential cooling, washing, and drying.
[0046] As a preferred technical solution of the present invention, the catalyst deposition in step (2) includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst.
[0047] Preferably, the concentrations of the Rh source, Cr source, and Co source are all 2 to 4 mg / mL, for example, 2 mg / mL, 2.4 mg / mL, 2.8 mg / mL, 3.2 mg / mL, 3.6 mg / mL, or 4 mg / mL, but are not limited to the listed values. Other unlisted values within the range are also applicable.
[0048] Preferably, the Rh source includes RhCl3, the Cr source includes K2CrO4, and the Co source includes Co(NO3)2.
[0049] Preferably, the method for depositing Rh atoms includes: adding an Rh source to an intermediate aqueous solution and irradiating it with light.
[0050] Preferably, the solid-liquid ratio of the intermediate and the Rh source is 1g:100~500μL, for example, it can be 1g:100μL, 1g:200μL, 1g:300μL, 1g:400μL or 1g:500μL, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0051] Preferably, the deposition method of Cr atoms includes: adding a Cr source to an aqueous solution of an intermediate on which Rh atoms have been deposited and then irradiating it with light.
[0052] Preferably, the solid-liquid ratio of the intermediate and the Cr source is 1g:100~200μL, for example, it can be 1g:100μL, 1g:120μL, 1g:140μL, 1g:160μL, 1g:180μL or 1g:200μL, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0053] Preferably, the method for depositing Co atoms includes: adding a Co source to an aqueous solution of an intermediate on which Cr atoms have been deposited and then irradiating it with light.
[0054] Preferably, the solid-liquid ratio of the intermediate and the Co source is 1g:100~200μL, for example, it can be 1g:100μL, 1g:120μL, 1g:140μL, 1g:160μL, 1g:180μL or 1g:200μL, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0055] Preferably, the power of the xenon lamp used for photodeposition is 280~320W, for example, it can be 280W, 290W, 300W, 310W or 320W, but is not limited to the listed values. Other values not listed within the value range are also applicable.
[0056] Preferably, the photodeposition time for each time is 5 to 10 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes, but not limited to the listed values. Other unlisted values within the range are also applicable.
[0057] It is worth noting that the deposition process of the catalyst described in this invention is accompanied by magnetic stirring, and a water bath drying treatment is also included before calcination.
[0058] As a preferred technical solution of the present invention, the calcination temperature in step (2) is 150~350℃, for example, it can be 150℃, 190℃, 230℃, 270℃, 310℃ or 350℃, etc., but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0059] Preferably, the calcination time in step (2) is 1 to 2 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours, but is not limited to the listed values. Other unlisted values within the range are also applicable.
[0060] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0061] Compared with the prior art, the present invention has the following beneficial effects:
[0062] (1) The spherical polyhedral strontium titanate single crystal particles provided by the present invention have no obvious boundaries on their crystal faces, and are close to the characteristics of infinitely many crystal faces. Their surfaces can be regarded as being composed of countless crystal faces with different orientations. Therefore, the anisotropic migration effect of photocarriers in such crystal particles is more obvious;
[0063] (2) The preparation method of the strontium titanate catalyst provided by the present invention has a clear principle, a simple process, readily available raw materials, stable control of particle spherical morphology, and is applicable to high-density light irradiation and long-term use scenarios. Attached Figure Description
[0064] Figure 1 Electron microscope image of the spherical polyhedral strontium titanate single crystal particles provided in Embodiment 1 of the present invention, with a scale bar of 100 nm;
[0065] Figure 2 The image shown is an electron microscope image of the spherical polyhedral strontium titanate single crystal particles provided in Embodiment 1 of the present invention, with a scale bar of 100 nm. Detailed Implementation
[0066] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0067] In one specific embodiment, the present invention provides spherical polyhedral strontium titanate single crystal particles with an average particle size of 200-500 nm, wherein the preparation method of the spherical polyhedral strontium titanate single crystal particles includes:
[0068] A mixed solution was obtained by ultrasonically dispersing a mixture of titanium source, strontium source, morphology modifier, aluminum source and alkaline solution for 5-10 minutes.
[0069] The molar ratio of the titanium source to the strontium source is 1:0.8~1.2; the content of the morphology modifier in the mixed solution is 1~3wt%, the content of the aluminum source is 0.1~0.5wt%, the average particle size is 50~500nm; and the pH value of the mixed solution is 9~12.
[0070] The mixed solution was subjected to a hydrothermal reaction at a stirring speed of 100~150 r / min, followed by washing 3~5 times and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
[0071] The hydrothermal reaction has a heating rate of 5~10℃ / min, a temperature of 150~200℃, and a time of 24~48h.
[0072] The drying process is carried out at a temperature of 80-100℃ for 5-10 hours.
[0073] In another specific embodiment, the present invention provides a strontium titanate catalyst, the strontium titanate catalyst comprising the above-mentioned spherical polyhedral strontium titanate single crystal particles, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles; the co-catalyst comprises Rh, Cr and Co;
[0074] The preparation method of the strontium titanate catalyst includes:
[0075] (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate;
[0076] The solid-state heat treatment temperature is 800~900℃, and the holding time is 5~10h;
[0077] (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst;
[0078] The catalyst deposition includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst;
[0079] The concentrations of the Rh source, Cr source, and Co source are all 2-4 mg / mL; the solid-liquid ratio of the intermediate to the Rh source is 1 g: 100-500 μL, the solid-liquid ratio of the intermediate to the Cr source is 1 g: 100-200 μL, and the solid-liquid ratio of the intermediate to the Co source is 1 g: 100-200 μL.
[0080] The power of the xenon lamp used for photodeposition is 280~320W, and the time for each photodeposition is 5~10min;
[0081] The calcination temperature is 150~350℃, and the time is 1~2h.
[0082] Example 1
[0083] This embodiment provides a spherical polyhedral strontium titanate single crystal particle, the preparation method of which includes:
[0084] A mixed solution was obtained by ultrasonically dispersing a mixture of titanium source (TiO2), strontium source (SrCl2), morphology modifier (ethylene glycol), aluminum source (Al2O3) and alkaline solution (sodium hydroxide) for 8 min.
[0085] The molar ratio of the titanium source to the strontium source is 1:1; the content of the morphology modifier in the mixed solution is 2 wt%, and the content of the aluminum source is 0.3 wt%; the pH value of the mixed solution is 12; and the average particle size of the Al2O3 is 200 nm.
[0086] The mixed solution was subjected to a hydrothermal reaction at a stirring speed of 120 r / min, followed by washing four times and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
[0087] The hydrothermal reaction has a heating rate of 10℃ / min, a temperature of 150℃, and a time of 36h.
[0088] The drying process is carried out at a temperature of 90°C for 8 hours.
[0089] The average particle size of the spherical polyhedral strontium titanate single crystal particles is 350 nm, and their electron microscope images are as follows. Figure 1 and Figure 2 As shown.
[0090] Example 2
[0091] This embodiment provides a spherical polyhedral strontium titanate single crystal particle, the preparation method of which includes:
[0092] A mixed solution was obtained by ultrasonically dispersing a mixture of titanium source (TiCl4), strontium source (Sr(OH)2), morphology modifier (glycerol), aluminum source (Al(OH)3), and alkaline solution (sodium hydroxide) for 5 min.
[0093] The molar ratio of the titanium source to the strontium source is 1:0.8; the content of the morphology modifier in the mixed solution is 1 wt%, and the content of the aluminum source is 0.1 wt%; the pH value of the mixed solution is 10; and the average particle size of the Al(OH)3 is 100 nm.
[0094] The mixed solution was subjected to a hydrothermal reaction at a stirring speed of 100 r / min, followed by washing three times and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
[0095] The hydrothermal reaction has a heating rate of 5℃ / min, a temperature of 120℃, and a time of 48h.
[0096] The drying process is carried out at a temperature of 80°C for 10 hours.
[0097] The average particle size of the spherical polyhedral strontium titanate single crystal particles is 200 nm.
[0098] Example 3
[0099] This embodiment provides a spherical polyhedral strontium titanate single crystal particle, the preparation method of which includes:
[0100] A mixed solution was obtained by ultrasonically dispersing a mixture of titanium source (tetrabutyl titanate), strontium source (SrCO3), morphology modifier (1,2-butanediol), aluminum source (Al2O3) and alkaline solution (sodium hydroxide) for 10 min.
[0101] The molar ratio of the titanium source to the strontium source is 1:1.2; the content of the morphology modifier in the mixed solution is 3 wt%, and the content of the aluminum source is 0.5 wt%; the pH value of the mixed solution is 10; and the average particle size of the Al2O3 is 500 nm.
[0102] The mixed solution was subjected to a hydrothermal reaction at a stirring speed of 150 r / min, followed by washing five times and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
[0103] The hydrothermal reaction has a heating rate of 10℃ / min, a temperature of 180℃, and a time of 24h.
[0104] The drying process is carried out at a temperature of 100°C for 5 hours.
[0105] The average particle size of the spherical polyhedral strontium titanate single crystal particles is 500 nm.
[0106] Example 4
[0107] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0108] In this embodiment, the content of aluminum source in the mixed solution is adjusted to 0.05 wt%.
[0109] Example 5
[0110] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0111] In this embodiment, the content of aluminum source in the mixed solution is adjusted to 0.8 wt%.
[0112] Example 6
[0113] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0114] In this embodiment, the content of the morphology modifier in the mixed solution is adjusted to 0.5 wt%.
[0115] Example 7
[0116] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0117] In this embodiment, the content of the morphology modifier in the mixed solution is adjusted to 4 wt%.
[0118] Example 8
[0119] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0120] In this embodiment, the temperature of the hydrothermal reaction is adjusted to 100°C.
[0121] Example 9
[0122] This embodiment provides a spherical polyhedral strontium titanate single crystal particle. The preparation method of the spherical polyhedral strontium titanate single crystal particle differs from that of Embodiment 1 only in that:
[0123] In this embodiment, the temperature of the hydrothermal reaction is adjusted to 250°C.
[0124] Comparative Example 1
[0125] This comparative example provides a strontium titanate single crystal particle, the preparation method of which differs from that of Example 1 only in that:
[0126] The mixing of the aluminum source is omitted in this comparative example.
[0127] Comparative Example 2
[0128] This comparative example provides a strontium titanate single crystal particle, the preparation method of which differs from that of Example 1 only in that:
[0129] This comparative example omits the mixing of the morphology modifiers.
[0130] Application Example 1
[0131] This application example provides a strontium titanate catalyst, which includes spherical polyhedral strontium titanate single crystal particles provided in Example 1, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles; the co-catalyst includes Rh, Cr and Co;
[0132] The preparation method of the strontium titanate catalyst includes:
[0133] (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate;
[0134] The solid-phase heat treatment temperature is 850℃, and the holding time is 8h;
[0135] (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst;
[0136] The catalyst deposition includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst;
[0137] The concentrations of the Rh source (RhCl3), Cr source (K2CrO4), and Co source (Co(NO3)2) are all 3 mg / mL; the solid-liquid ratio of the intermediate to the Rh source is 1 g:300 μL, the solid-liquid ratio of the intermediate to the Cr source is 1 g:150 μL, and the solid-liquid ratio of the intermediate to the Co source is 1 g:150 μL.
[0138] The xenon lamp used for photodeposition has a power of 300W, and the photodeposition time for each time is 8 minutes.
[0139] The calcination temperature was 250℃ and the time was 1.5h.
[0140] Application Example 2
[0141] This application example provides a strontium titanate catalyst, which includes spherical polyhedral strontium titanate single crystal particles provided in Example 2, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles; the co-catalyst includes Rh, Cr and Co;
[0142] The preparation method of the strontium titanate catalyst includes:
[0143] (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate;
[0144] The solid-phase heat treatment temperature is 800℃, and the holding time is 10h;
[0145] (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst;
[0146] The catalyst deposition includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst;
[0147] The concentrations of the Rh source (RhCl3), Cr source (K2CrO4), and Co source (Co(NO3)2) are all 2 mg / mL; the solid-liquid ratio of the intermediate to the Rh source is 1 g: 500 μL, the solid-liquid ratio of the intermediate to the Cr source is 1 g: 200 μL, and the solid-liquid ratio of the intermediate to the Co source is 1 g: 200 μL.
[0148] The xenon lamp used for photodeposition has a power of 280W, and the photodeposition time is 10 minutes each time.
[0149] The calcination temperature was 150℃ and the time was 2 hours.
[0150] Application Example 3
[0151] This application example provides a strontium titanate catalyst, which includes spherical polyhedral strontium titanate single crystal particles provided in Example 2, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles; the co-catalyst includes Rh, Cr and Co;
[0152] The preparation method of the strontium titanate catalyst includes:
[0153] (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate;
[0154] The solid-phase heat treatment temperature is 900℃, and the holding time is 5h;
[0155] (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst;
[0156] The catalyst deposition includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst;
[0157] The concentrations of the Rh source (RhCl3), Cr source (K2CrO4), and Co source (Co(NO3)2) are all 4 mg / mL; the solid-liquid ratio of the intermediate to the Rh source is 1 g:100 μL, the solid-liquid ratio of the intermediate to the Cr source is 1 g:100 μL, and the solid-liquid ratio of the intermediate to the Co source is 1 g:100 μL.
[0158] The xenon lamp used for photodeposition has a power of 320W, and the photodeposition time for each step is 5 minutes.
[0159] The calcination temperature was 350℃ and the time was 1 hour.
[0160] Application Example 4
[0161] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0162] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 4.
[0163] Application Example 5
[0164] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0165] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 5.
[0166] Application Example 6
[0167] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0168] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 6.
[0169] Application Example 7
[0170] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0171] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 7.
[0172] Application Example 8
[0173] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0174] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 8.
[0175] Application Example 9
[0176] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0177] In this application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Example 9.
[0178] Application Example 10
[0179] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0180] In this application example, the temperature of the solid-phase heat treatment in step (1) is adjusted to 700℃.
[0181] Application Example 11
[0182] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0183] In this application example, the temperature of the solid-phase heat treatment in step (1) is adjusted to 1000℃.
[0184] Application Example 12
[0185] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0186] In this application example, the cocatalyst is adjusted to Rh, Cr and Mn; and the Co source in step (2) is adjusted to an equal amount and concentration of manganese nitrate solution.
[0187] Application Example 13
[0188] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0189] This application example omits the catalyst deposition process described in step (2).
[0190] Application Example 14
[0191] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0192] In this application example, the calcination temperature in step (2) is adjusted to 100°C.
[0193] Application Example 15
[0194] This application example provides a strontium titanate catalyst, which differs from Application Example 1 only in that:
[0195] In this application example, the calcination temperature in step (2) is adjusted to 380°C.
[0196] Comparative Application Example 1
[0197] This comparative example provides a strontium titanate catalyst, which differs from Example 1 only in that:
[0198] In this comparative application example, the spherical polyhedral strontium titanate single crystal particles are modified to be the spherical polyhedral strontium titanate single crystal particles provided in Comparative Example 1.
[0199] Comparative Application Example 2
[0200] This comparative example provides a strontium titanate catalyst, which differs from Example 1 only in that:
[0201] In this comparative application example, the spherical polyhedral strontium titanate single crystal particles are modified to the spherical polyhedral strontium titanate single crystal particles provided in Comparative Example 2.
[0202] Photocatalytic water splitting hydrogen production efficiency test:
[0203] The efficiency of photocatalysts for hydrogen production through water splitting provided in the above application examples and comparative application examples was tested. The testing method included:
[0204] 0.1 g of strontium titanate catalyst was added to 70 mL of deionized water. After stirring at 120 r / min, the reactor was evacuated to a vacuum and irradiated with a xenon lamp (300 W, full arc). 1 mL of gas was extracted every half hour, and the hydrogen content was detected using gas chromatography. The hydrogen generation rate was tested under 300 W full-band light irradiation conditions, and the results are shown in Table 1.
[0205] Table 1
[0206]
[0207] According to Table 1, the following points can be observed:
[0208] (1) Comprehensive analysis of application examples 1-3 shows that the method provided by the present invention can obtain spherical polyhedral strontium titanate single crystal particles, and then the photocatalytic hydrogen production efficiency can be further improved by depositing a catalyst.
[0209] (2) Comprehensive analysis of application example 1, application example 4-7 and comparative application example 1-2 shows that spherical polyhedral strontium titanate single crystal particles can only be obtained by controlling the amount of raw materials and their synergistic effects.
[0210] If the amount of aluminum source used is too low, the lattice will not be fully filled, resulting in a decrease in hydrogen production rate. If the amount used is too high, the spherical morphology will be irregular, resulting in a decrease in hydrogen production rate. If the use of aluminum source is omitted, a large number of lattice defects will occur, resulting in a significant decrease in hydrogen production rate.
[0211] If the amount of the morphology modifier is too low or too high, it will result in irregular spherical morphology, thereby reducing the hydrogen production rate of the catalyst; if the use of the morphology modifier is omitted, it is impossible to control the regular morphology of strontium titanate, and the hydrogen production rate will be greatly reduced.
[0212] (3) Comprehensive analysis of Application Example 1 and Application Example 8-9 shows that if the temperature is too high during the hydrothermal reaction process, the spherical morphology will be irregular and the hydrogen production rate will be reduced. If the temperature is too low, the perovskite lattice and spherical morphology cannot be formed, and the hydrogen production rate will be greatly reduced.
[0213] (4) Comprehensive analysis of Application Example 1 and Application Example 10-11 shows that when the temperature of the solid phase heat treatment is too high, it cannot compensate for the surface lattice defects, which leads to a significant reduction in hydrogen production rate. When the temperature is too low, it will result in an irregular stepped morphology on the surface, which will also reduce the hydrogen production rate.
[0214] (5) Comprehensive analysis of Application Example 1 and Application Examples 12-13 shows that the deposition of the co-catalyst will further improve the photocatalytic performance of the strontium titanate particles;
[0215] If the cocatalyst is changed to Rh, Cr and Mn, the photocatalytic performance will decrease, which further illustrates the compatibility of Rh, Cr and Co with the spherical polyhedral strontium titanate single crystal particles.
[0216] (6) Comprehensive analysis of Application Example 1 and Application Examples 14-15 shows that the calcination in step (2) will affect the activity of the co-catalyst on the surface of the strontium titanate particles. If the calcination temperature is too high, some co-catalysts will undergo chemical reactions and their activity will decrease. If the temperature is too low, some co-catalysts will have lattice defects and their activity will decrease.
[0217] In summary, this invention uses a hydrothermal method to prepare regular spherical polyhedral strontium titanate single crystal particles using titanium, strontium, and aluminum sources, effectively exposing multiple micro-crystal faces with different orientations such as (100), (110), and (111). When applied to the field of photocatalysis, it can exhibit a high rate of hydrogen production through photocatalysis under sunlight.
[0218] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A method for preparing spherical polyhedral strontium titanate single crystal particles, characterized in that, The preparation method includes: A mixed solution was obtained by ultrasonic dispersion of a titanium source, a strontium source, a morphology modifier, an aluminum source, and an alkaline solution. The mixed solution was subjected to a hydrothermal reaction, followed by washing and drying to obtain the spherical polyhedral strontium titanate single crystal particles.
2. The preparation method according to claim 1, characterized in that, The titanium source includes any one or a combination of at least two of TiO2, TiCl4, or tetrabutyl titanate. Preferably, the strontium source includes any one or a combination of at least two of Sr(OH)2, SrCl2, or SrCO3; Preferably, the molar ratio of the titanium source to the strontium source is 1:0.8~1.2; Preferably, the morphology modifier comprises any one or a combination of at least two of ethylene glycol, glycerol, butanetetraethanolamine, or propylene glycol; Preferably, the content of the morphology modifier in the mixed solution is 1-3 wt%; Preferably, the aluminum source includes Al2O3 and / or Al(OH)3; Preferably, the average particle size of the aluminum source is 50~500nm; Preferably, the aluminum source content in the mixed solution is 0.1~0.5 wt%; Preferably, the concentration of the alkaline solution is 1~2 mol / L; Preferably, the pH value of the mixed solution is 9-12.
3. The preparation method according to claim 2, characterized in that, The temperature of the hydrothermal reaction is 150~200℃; Preferably, the heating rate of the hydrothermal reaction is 5~10℃ / min; Preferably, the hydrothermal reaction takes 24-48 hours; Preferably, the hydrothermal reaction is accompanied by stirring, and the stirring speed is 100~150 r / min.
4. The preparation method according to any one of claims 1-3, characterized in that, The washing is performed 3 to 5 times; Preferably, the drying temperature is 80~100℃; Preferably, the drying process takes 5 to 10 hours.
5. A spherical polyhedral strontium titanate single crystal particle, characterized in that, The spherical polyhedral strontium titanate single crystal particles are obtained by the preparation method described in any one of claims 1-4; The average particle size of the spherical polyhedral strontium titanate single crystal particles is 200~500 nm.
6. A strontium titanate catalyst, characterized in that, The strontium titanate catalyst includes the spherical polyhedral strontium titanate single crystal particles as described in claim 5, and a co-catalyst deposited on the surface of the spherical polyhedral strontium titanate single crystal particles; The co-catalysts include Rh, Cr, and Co.
7. The strontium titanate catalyst according to claim 6, characterized in that, The preparation method of the strontium titanate catalyst includes: (1) The spherical polyhedral strontium titanate single crystal particles were subjected to solid-state heat treatment to obtain an intermediate; (2) The intermediate is subjected to catalyst deposition and calcination in sequence to obtain the strontium titanate catalyst.
8. The strontium titanate catalyst according to claim 7, characterized in that, The solid-state heat treatment temperature in step (1) is 800~900℃; Preferably, the heat treatment time for solid phase heat treatment in step (1) is 5~10h.
9. The strontium titanate catalyst according to claim 6, characterized in that, Step (2) of the catalyst deposition includes: sequentially photodepositing Rh atoms, Cr atoms and Co atoms on the intermediate using Rh source, Cr source and Co source to complete the deposition of the catalyst; Preferably, the concentrations of the Rh source, Cr source, and Co source are all 2-4 mg / mL; Preferably, the solid-liquid ratio of the intermediate and the Rh source is 1g:100~500μL; Preferably, the solid-liquid ratio of the intermediate and the Cr source is 1g:100~200μL; Preferably, the solid-liquid ratio of the intermediate and the Co source is 1g:100~200μL; Preferably, the power of the xenon lamp used for photodeposition is 280~320W; Preferably, the photodeposition time for each step is 5 to 10 minutes.
10. The strontium titanate catalyst according to claim 7, characterized in that, The calcination temperature in step (2) is 150~350℃; Preferably, the calcination time in step (2) is 1~2 hours.